There are numerous standards for encoding numeric and other information in visual form, such as the Universal Product Codes (UPC) and/or European Article Numbers (EAN). These numeric codes allow businesses to identify products and manufactures, maintain vast inventories, manage a wide variety of objects under a similar system and the like. The UPC and/or EAN of the product is printed, labeled, etched, or otherwise attached to the product as a dataform.
Dataforms are any indicia that encode numeric and other information in visual form. For example, dataforms can be barcodes, two dimensional codes, marks on the object, labels, signatures, signs etc. Barcodes are comprised of a series of light and dark rectangular areas of different widths. The light and dark areas can be arranged to represent the numbers of a UPC. Additionally, dataforms are not limited to products. They can be used to identify important objects, places, etc. Dataforms can also be other objects such as a trademarked image, a person's face, etc.
Devices, such as, for example, a laser based barcode scanner, can be used to decode dataforms and automatically obtain information about a product from them. Known laser scanners comprise beam shaping optics to form their laser beams. To improve scanner performance, for example, with low contrast and poorly printed barcodes, an elliptically shaped laser spot is preferable. An elliptically shaped laser spot can be formed by elongating the vertical height of the laser spot, for example by adding an optical component with astigmatism to the beam shaping optics. An optical component with astigmatism can be, for example, a cylindrically shaped lens or mirror. An accurate orientation of the cylindrical component in the scanner is critical for consistent scanner performance. For example, if the lens is off by 90 degrees, the laser spot is elongated in a horizontal direction and does not provide performance enhancements.
FIG. 2 illustrates an exemplary beam shaping assembly 200 comprising a laser 205, a focusing lens 215, a cylindrical lens 220, a lens holder 210 and an aperture 225. Laser light is focused by the focusing lens 215, elongated by the cylindrical lens 220 and further shaped by the aperture 225. The aperture 225 can have a non-rotationally symmetrical shape, such as, for example, a rectangle, an ellipse, etc. An exemplary method of creating an aperture is to die cast a hole in an opaque material, such as, the lens holder. In general it can be difficult to control the quality of the size and edges of the aperture in a mass production environment. This leads to aperture defects such as, for example, flash at the edge of the aperture and out-of-spec sizes.
Although not shown, the lens holder 210 comprises alignment features that help properly orient the lens module in a scanner. When the assembly 200 is constructed, it is very important to properly orient the cylindrical lens 220 with the aperture 225 and/or the alignment features of the lens holder, or else the laser beam will be improperly shaped when the lens module is placed in the scanner.
Accordingly, there is a desire to simplify the construction of the beam shaping assembly of scanners. In addition, there is a desire to improve the quality of mass produced apertures.